SWAPA chimes in on TR use and Performance

magsau

Veteran
Aug 20, 2002
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Subject: WINTER WEATHER OPS Safety Alert 2006-01
From the Southwest Airline Pilots Association (SWAPA)
January 23, 2006
WINTER WEATHER OPS Safety Alert 2006-01

Although there is very little that can be discussed concerning the MDW Flt. 1248 accident of Dec. 8, 2005, there are some facts that have come to light that need to be highlighted as at least three months of winter remain.

There is a distinct difference in how the OPC computes landing and RTO performance for the classic fleet of Boeing 737's and the NG -700 aircraft. The classic OPC does not utilize any reverse thrust credit while calculating the stopping margin; this is in line with the certification procedure for the aircraft. The NG aircraft OPC's however use Boeing proprietary software that factors in the use of reverse thrust for these same calculations, which in our estimation does not give you, the operator, a realistic margin of safety when interpreting how much stopping margin is actually available. Obviously SWAPA is not in the position, nor do we have the authority to dictate operational procedures for Southwest Airlines, but in our opinion it would seem wise to review the -700 OPC data and when the runway is short, contaminated, or braking action reports are less than good, that you give consideration to programming the OPC to MEL the thrust reversers and note the difference in stopping margin. This applies to both landing performance and RTO performance; make the landing or departure decision accordingly.

Braking action reports and runway friction reports very often do not correlate. The braking action reports are subjective and not only is the MU interpretation subjective, the MU value does not translate to any braking action value. One can find a poor braking report followed by a MU value that ranks as the lower end of GOOD, so be very careful when relying upon the combination of both. All Part 25 certificated aircraft have their landing performance derived from dry, uncontaminated runway performance data that then has various equations applied. The formula for these equations appears to have come from a 1961 Convair 880 test that was conducted by the FAA.
The point in explaining this is that when your stopping margin begins to get a little thin it would be a good time to review all of your options as the data that you are utilizing may not actually reflect the true stopping distance required. If in fact what we are discovering is true, then the equations that were developed were developed from a first generation swept wing pure turbojet transport. The adaptation to the current NG B-737 may not be as accurate as we have thought.


Boeing has provided us a very good aircraft to operate and one that has a great record. As pilots, we often take the performance values for granted; in most conditions that is a safe and wise decision. While operating in winter weather conditions, heavy aircraft, short runways, etc., give extra consideration to your dispatch release, the fuel on board, the runway condition, possible tailwind component, and how closely your aircraft might be to its operating limit and safety margin for that particular approach or departure.

We operate from some relatively short runways in some cities to fly long distances and the RTO stopping margin can be a factor. ISP comes to mind where we routinely use RWY 33L which is only 5186 feet long. A -700 in excess of 130,000 pounds will not have much in the way of RTO stopping margin departing that runway. Using the same example, a 125,000-pound -700 will not have much stopping margin while landing on that runway. Consider less tanker fuel coming in and utilizing RWY 6/24 as opposed to the often advertised 15/33. ISP in particular causes us concern as it is a high use General Aviation airport and the ATIS and active runway are often tailored to that spectrum of aviation as opposed to Part 25 aircraft that could have a greater safety margin by utilizing a longer runway. Just because the 15R/33L runway is being advertised does not mean that you have to use it.

Examine the OPC for all runways and choose the stopping margin that gives you the better safety cushion. This thought process applies to MDW as well. Historically, the active runway at MDW is predicated upon ORD landing flows. If RWY 13C is better suited for your arrival then make the request if it makes sense. MDW ATC can provide you with that runway if asked and given the reason why. Take this type of thought process and apply it to any airport that you might be operating to or from and make the decisions that you need to make accordingly. As always, the captain is the final authority on the safe operation of the aircraft.

Another issue that has come to light is the periodic difficulty in actuating reverse thrust in the -700 aircraft. Through testing we have found that the slightest forward movement of the Thrust Levers will mechanically keep the Thrust Reverser Levers from unlocking. It is very important that the Thrust Levers be flat against the Idle Stop before attempting to actuate the Thrust Reversers. If you experience any difficulty in actuating the Thrust Reversers, assure that the Thrust Levers are physically flat against the Idle Stop and re-attempt. If the problem persists, then make a logbook entry and have maintenance examine the system.

-SWAPA Air Safety Committee
 
The NTSB says this about the accident:

Recommendation comes after plane overran runway and boy died
Friday, January 27, 2006; Posted: 2:13 p.m. EST (19:13 GMT)

WASHINGTON (CNN) -- The National Transportation Safety Board is urging that commercial airplane pilots change the way they calculate stopping distances on slippery runways to avoid a crash, such as the one in Chicago that killed a child.
"We believe this recommendation needs the immediate attention of the FAA since we will be experiencing winter weather conditions in many areas of our nation for several more months to come," NTSB Acting Chairman Mark V. Rosenker was quoted in a news release issued by the board.
The NTSB wants the Federal Aviation Administration to prohibit airlines from calculating the effect of a plane's thrust reversers into the formula that figures what distance is needed to land when runways are slick.
The urgent recommendation comes from an NTSB investigation into what caused a Southwest Airlines flight, landing at Midway Airport in a snowstorm on December 8, to roll off the end of the runway -- where it tore through two fences and stopped in an intersection, hitting two cars. A 6-year-old boy in one of the cars was killed.
The pilots had used a laptop computer to calculate how far the plane needed to go to land, the NTSB said. When the runway's condition was entered as "wet-poor," the computer calculated they would be able to stop with 30 feet to spare.
But the calculations took into consideration that engine thrust reversers would be deployed at touchdown. Instead, the NTSB said, "flight data recorder information revealed that the thrust reversers were not deployed until 18 seconds after touchdown, at which point there was only about 1,000 feet of usable runway remaining."
Without the thrust reversers, the calculation would have shown a safe landing was not possible, it said.
"As a result," the board said in its recommendation letter to the FAA, "a single event, the delayed deployment of the thrust reversers, can lead to an unsafe condition, as it did in this accident."
The NTSB said the FAA already prohibits the inclusion of thrust reversers in calculations in some cases.
 
"The NG aircraft OPC's however use Boeing proprietary software that factors in the use of reverse thrust for these same calculations, which in our estimation does not give you, the operator, a realistic margin of safety when interpreting how much stopping margin is actually available. Obviously SWAPA is not in the position, nor do we have the authority to dictate operational procedures for Southwest Airlines, but in our opinion it would seem wise to review the -700 OPC data and when the runway is short, contaminated, or braking action reports are less than good, that you give consideration to programming the OPC to MEL the thrust reversers and note the difference in stopping margin. This applies to both landing performance and RTO performance; make the landing or departure decision accordingly."

It took driving through a fence to realize that TR's are part of the OPC calculations? WTFO? Are the assumptions for the chart data not indicated on the performance chart? A little late now to learn this information. You can bet a team of lawyers will be reviewing this alarming information.

http://www.baumhedlundlaw.com/aviation/Sou...ht1248Crash.htm

Speak of the devil.
 
There is no chart available to the pilots. The data is only presented as output on a single computer screen.

So there are no conditions or requirements listed for how the data was derived? That sound like something the attorney would love to know. Sounds like a huge liability to be using data that you are not sure of the conditions. Do you have a selection for TR use and no TR use? Is it standard to factor in TR use in the data or do you have to deselect it if they are deferred. Seems like it should be the other way around. Standard data should be without and you should have the option of advisory data only with use of TR's. Since you really don't know if they are going to be deployed under the base assumptions, whatever those might be.
 
So there are no conditions or requirements listed for how the data was derived? That sound like something the attorney would love to know. Sounds like a huge liability to be using data that you are not sure of the conditions. Do you have a selection for TR use and no TR use? Is it standard to factor in TR use in the data or do you have to deselect it if they are deferred. Seems like it should be the other way around. Standard data should be without and you should have the option of advisory data only with use of TR's. Since you really don't know if they are going to be deployed under the base assumptions, whatever those might be.
Maybe you should testify as a expert witness for the plantiff.
 
All SWA would need to do to raise a reasonable doubt is to let them see your posts here.


Hey KC where is that data on the $50 a bbl for UAL oil? You were going to provide some proof of what you claim correct? Oh I forgot you are liar that makes up crap to fit your story. $67 a bbl buddy and UAL is OK. Don't forget we have some hedges in place.
 
Hey KC where is that data on the $50 a bbl for UAL oil? You were going to provide some proof of what you claim correct? Oh I forgot you are liar that makes up crap to fit your story. $67 a bbl buddy and UAL is OK. Don't forget we have some hedges in place.
I promise I won't gloat a year or so from now when you're asked for more concessions. Does Ted fly international?
 
I promise I won't gloat a year or so from now when you're asked for more concessions. Does Ted fly international?

How about more facts to back up you liars mouth? You claimed $50 a bbl. Now show me where those numbers are in print.

To answer you question about TED. Yes TED does fly intl. How about LUV? Perhaps they would be international if they slid off the runway in ELP and wound up in MEX.
 
How about more facts to back up you liars mouth? You claimed $50 a bbl. Now show me where those numbers are in print.

To answer you question about TED. Yes TED does fly intl. How about LUV? Perhaps they would be international if they slid off the runway in ELP and wound up in MEX.
I'm so thrilled to hear that TED flies international. I suppose it won't be too much longer that will be seeing ORD-LGW flights in Ted colors. Bet you'll look good up there in the front seat... your powerful skygod speaking voice coming over the PA to announce that because we might hit turbulence within the next 5 hours, you're going to ask the FA's to return to their seats. Then you can tell all the folks on the left side of the plane that if they look down thru the clouds, they can see Ireland. Maybe you can put a tip jar by the cockpit door so that passengers who swoon at the sight and sound of a bona fide skygod can toss you a couple of bucks to cover the entertainment. For an extra five bucks, you might let them touch the sleeve of your coat. Oh yeah, I almost forgot, my proctologist is pretty sure he knows you.
 
[quote name='magsau' date='Jan 28 2006, 12:50 AM' that the thrust reversers were not deployed until 18 seconds after touchdown, at which point there was only about 1,000 feet of usable runway remaining."
PILOT ERROR
 
I'm so thrilled to hear that TED flies international. I suppose it won't be too much longer that will be seeing ORD-LGW flights in Ted colors.

LGW= London Gatwick. Sorry we fly to LHR(london Heathrow) The real London airport. Got any more lies and misinformation you care to throw out?

WTF are you doing the TED reference for. I could care less what the airline is called or the color it is painted as long as it survives. I believe SWA has done a good job of proving that god awful paint jobs still make money. It is all the same KC (mainline and TED) ,the only difference is we had to shorten the name to attract the customers of the likes that SWA flies around. Could not have too many letters or words. Three was about as many letters as the average SWA pax could comprehend. Seems to be working :)

You should run along and get busy on that $50 bbl claim you made. Hate to see you made out to be a LIAR in front of your fans. But you made a claim now how about backing it up? Waiting patiently while you try to avoid the facts.